It has been proposed more than once that Thai Immigration issue Expat photo ID cards (for those on long stay Visas and Extensions. With such an Expat Card there would be no need for Residency Certificates, Carrying the Passport for routine out of the house short travel, no need for proofs in applying for Drivers Licenses other than a passport, etc. Other countries do this - even in Asia.
You can only get one 30 day Extension to the original 30 day Exempt Entry. You will have to go to Penang, Malaysia (closest place) to the Thai Consulate and apply for a 60 day Tourist Visa (which you can later Extend at the Phuket Immigration office.
Tod the only qualifier I should have added is Some as in 'Some Companies'. And from reading on other venues it is hardly just the South and the Islands. Of course many employers are able to and do the correct thing. But what I describe exists.
And as Lloyd accurately added not paying or not wanting to pay the minimum wage to Farang employees adds to the problem.
Companies don't want to sponsor Extensions for B Visa employees. One Farang employee garners 2 to 4 Thai employees. More than one Farang = times 2 / times 3. Even if done as "shadow" employees the Social Security tax must be paid. After the minimum wage increase several months ago - effective April 1 - the S.S. payment for each Thai employee equals nearly 1000 baht. If the company actually hired these Thai employees then costs spiral up.
With currently valid Reentry Permits - I suppose they could be cancelled - leaving the Non O intact. Then no rush to leave Thailand as you would still be on a valid visa status